Boxgirder bridge
There is no point of difference between grade separator or a flyover bridge.The point is that a grade separator can either be a flyover or an under pass, that is any structure which separates the uniform grade of a running highway into two different grades. Also considering the cost fact grade saperator is more cost effective as far as my knowledge.
arch, span, viaduct, flyover, overpass
Flyover connects two points usually as an alternate route to what is beneath. Its purpose is to shorten or quicken the travel time and ease out traffic congestion. Bridge is used to connect two points and acts as an essential link between the connecting points. Its main purpose is to establish a link between the points which is other wise inaccessible via road transport. Although neither has anything to do with natural or man-made as suggested in other answers.
The overhead traveling bridge crane existed as early as 1860
go towards the waterfall and it's a big rock covered in moss between the waterfall and the bridge
Flyover connects two points usually as an alternate route to what is beneath. Its purpose is to shorten or quicken the travel time and ease out traffic congestion. Bridge is used to connect two points and acts as an essential link between the connecting points. Its main purpose is to establish a link between the points which is other wise inaccessible via road transport. Neither has anything to do with natural or man-made as suggested in other answers.
A bridge with overhead cables to support it.
giant cables and abutments
flyover
There are no similarities between the two bridges. They are completely and totally different.
The span is the distance between supports. The sum of the span lengths is the bridge length.
AbutmentA retaining wall supporting the ends of a bridge or viaduct.Pierssupport if continuous bridge